What Does AC/DC Mean (Not the Rock Band)

We all love AC/DC around here - no, not the rock band. Well, yes, the rock band, but also their namesake. We’re talking about alternating current (AC) and direct current (DC) - different types of voltage that provide power in varying ways.  

What are AC and DC power?

Electricity flows in either AC or DC - both are electrical currents in that they’re the flow of electrons, but where they differ is in their direction of flow. Alternating current (AC) periodically reverses and switches direction, sometimes going forward and then going backward, while a direct current (DC) only flows in one single direction.

Visually, when shown on a graph, a DC current looks like a flat line, while AC flow takes the shape of a wave-like pattern to signify its oscillating repetition. AC can be produced using a special kind of electrical generator called an alternator in which a loop of wire is spun inside of a magnetic field, inducing a rotation along the wire. As the wire spins, it periodically enters a different magnetic polarity, which causes the back-and-forth flow of the current.

DC, on the other hand, provides a steady current that flows only one way. This can be generated from a battery, the use of a device called a “rectifier” that converts AC to DC or an AC generator equipped with a “commutator” that produces direct current.

DC power is particularly attributed to the work of Thomas Edison, while Nikola Tesla expanded into creating an AC current that could be easily converted into higher and lower voltages more easily using a transformer, alternating and reversing direction 60 times per second (50 in Europe). The frequency of a direct current is zero. 

What are the different ways to generate AC and DC? 

AC and DC provide power in different ways - AC is delivered to businesses and residencies and is the kind of energy that you typically use when you plug in a TV, fan, bedside lamp or a kitchen appliance into a wall socket. Alternating current is the best way to transmit electricity over large distances with the source of this current located far away, as it is safer and can provide more power.  

DC, however, is used when you use a flashlight, for example, as the power source is the battery cell inside of it. DC voltage cannot travel very far before it begins to lose energy.

If I’m on a laptop, am I using AC or DC power? 

Both! You’re using both kinds of current. The plug that you insert into your computer sends a direct current to the computer’s battery while receiving that charge from an AC plug that goes into the wall. The brick-like block in between the wall plug and your computer is your power adapter that transforms AC to DC power.  

What are some examples of AC and DC applications?

Home and office outlets are nearly always using AC due to their relative ease in transporting it across long distances. Less energy is lost in electrical power transmission at high voltages (over 110kV). Higher voltages equal lower currents, and lower currents equal less heat generated in the power line due to resistance. AC power can be easily converted from high voltages with the use of transformers and can power electric motors and large appliances like refrigerators and dishwashers.

Anything that runs off of a battery plugs into a wall with an AC adapter, or uses a USB cable for a charge is relying on DC power. Some of these electronics include cell phones, flashlights, and hybrid vehicles. Most of your handheld electronics are running on DC.

Is there a war of the currents?

Yes! Nearly every home and business are wired for AC, but this was a long time coming. In the late 1880s, inventors all over the United States and Europe battled for relevance in a fight of AC and DC supremacy. In 1886, a Budapest-based electric company called Ganz Works lit the entire city of Rome with AC, while Edison built 121 DC power stations across the U.S. by the next year. The battle was essentially won the next year when Pittsburgh industrialist George Westinghouse bought Tesla’s AC patents, sending AC power into the homes of Americans nationwide.  

The two haven’t always gotten along, and historically they haven’t mixed very well. While establishments and homes will continue to be powered by AC, the more LEDs, solar cells, electric vehicles, and mobile electronics enter our lives the more prevalent DC power will be. Advancements in DC are on the rise as methods to convert DC to higher and lower voltages with less electricity loss are continuing to develop. 

So will there be a resolution to the war of the currents? The more they work side-by-side, perhaps AC and DC will come together and be friendly with each other after all. 

How about you? If there’s an electrical battle in your household or business, or if you need to upgrade your electrical panel, our team here at Pacman Electric is happy to evaluate your situation and get you going with any and all electrical needs you have.  

Call us today at (924) 577-7923. We look forward to answering your questions, hearing your concerns, and discussing any issues you may be having!

Chris Pacchioli